1. Field of the Invention
The present invention relates to biocidal polymers for disinfection of halogen-sensitive organisms. In particular, polymers of cyclic N-halamines are provided. Additionally, provided are methods for disinfection comprising contacting a habitat for halogen-sensitive organisms with a biocidal amount of a polymer of a cyclic N-halamine. Such habitats can include but are not limited to air and gas streams, water such as in potable water supplies, swimming pools, industrial water systems and air conditioning systems, organic fluids, hard surfaces and fabric materials.
2. Background Art
Current disinfectants which are in use for purposes such as disinfecting water, as can be used in potable water supplies, swimming pools, hot tubs, industrial water systems, cooling towers, spacecraft, waste water treatment plants, air conditioning systems, military field units, camping expeditions, and in other sanitizing applications, as well as of organic fluids such as oils, paints, coatings, and preservatives, and in various medicinal applications all have serious limitations. Sources of the most commonly used disinfectant free halogen (chlorine, bromine, or iodine) are effective disinfectants, but free halogen is corrosive toward materials, toxic to marine life, reactive with organic contaminants to produce toxic trihalomethanes, irritating to the skin and eyes of humans, and relatively unstable in water, particularly in the presence of sunlight or heat. Ozone and chlorine dioxide are also effective disinfectants, but they are not persistent in water such that they have to be replenished frequently; they also may react with organic contaminants to produce products having unknown health risks. Combined halogen compounds such as the commercially employed hydantoins and cyanurates as well as the recently discovered oxazolidinones (Kaminski et al., U.S. Pat. Nos. 4,000,293 and 3,931,213) and imidazolidinones (Worley et al., U.S. Pat. Nos. 4,681,948; 4,767,542; 5,057,612; 5,126,057) are much more stable in water than are free halogen, ozone, and chlorine dioxide, but in general they require longer contact times to inactivate microorganisms than do the less stable compounds mentioned.
A characteristic which all of the aforementioned disinfectants have in common is that they are soluble to some extent in water. Thus humans or animals drinking or contacting the water are exposed to the compounds and products of their reactions with contaminants which could cause health risks in some situations.
Polymeric quaternary ammonium anionic-exchange resins have been known for many years (see for example U.S. Pat. Nos. 2,595,225; 2,923,701; 2,980,657; 2,980,634; 3,147,218; 3,288,770; 3,316,173; 3,425,790; 3,462,363; 3,554,905; 3,539,684; 3,817,860; 3,923,665; 4,187,183; 4,349,646; 4,420,590). The "polyquats" have important limitations. Most are soluble in water which means that they could pose a threat to humans or animals drinking or contacting water containing them. The insoluble polyquats tend to release fairly high concentrations of free halogen, and the most effective of these release the triiodide ion, which is undesirable with respect to dietary intake for certain groups of the population (U.S. Pat. No. 4,349,646). Such compounds are also generally expensive to manufacture.
Functionally modified poly(styrene-divinylbenzene) compounds containing N-chlorinated sulfonamide moieties have been prepared and shown to have biocidal properties (see for example Emerson et al., Ind. Eng. Chem. Prod. Res. Dev., 17:269 (1978); Ind. Eng. Chem. Res., 29:448 (1990); Ind. Eng. Chem. Res., 30:2426 (1991)). However, these N-halamines do not contain the N-Cl or N-Br moieties in a cyclic ring and are hence not expected to be as stable toward release of free halogen as those to be described herein. In fact, they are known to release greater than 1 milligram per liter of free chlorine when the pH of water flowing through them is greater than 7.0.
Therefore, there is a great need for insoluble broad-spectrum disinfectants which kill microorganisms upon contact, but which do not leach undesirable organic contaminants into the medium to be disinfected, and which maintain a very low concentration of free halogen (less than 1 milligram per liter) in such medium. There is also a need for methods to treat many various habitats in which halogen-sensitive microorganisms dwell.